MovieBattles II (http://www.moviebattles.com)
A progressive, tactical, class-based, team-orientated Multiplayer Total Conversion. Classes inspired by characters seen in the movies. An active and competitive community. More activity than vanilla JA even on low times. New weaponry, a totally new Saber System, new animations. Re-enact the fast combat seen in the movies. Try it out if you're up for constant action.

Of course can't forget:
ForceMod 3 (http://fm.mt-wudan.com)
Choose from 29 unique classes in 6 different Factions (Jedi, Clonetrooper, Gungan, Soldier, HotShots etc.). If you enjoy either hacking up gunners with a lightsaber or hunting Jedi as a bounty hunter, ForceMod may be the mod for you.

Aye, a few skilled people still stick with the game. I find myself being pretty active in JKA. However, many people have moved on, seeing that funding was cut to the game. There are a few mods out there trying to keep it alive.

MovieBattles II, as they posted, is a mod that is kind of like BattleFront.

ForceMod III is JKA but in a class-based system.

JA+ is an admin mod that also is an actual jka combat mod...meaning it adds new moves, abilities, bug fixes, and the sort for the original gameplay style.